Rolling bearings which are reduced in frictional resistance by interposing balls or rollers between an outer race and an inner race have been known from the past and in such rolling bearings a retainer cage is typically interposed between the balls or the rollers so as to reduce the frictional forces arising from direct contact between the balls or the rollers.
However, even though a conventional retainer cage is quite capable of retaining the balls or the rollers at an equal interval between an outer race and an inner race, it necessarily rotates around the center of rotation of the bearing, interposed between the inner race and the outer race, involving some rubbing motion relative to the balls or rollers, the inner race and the outer race which surround the retainer cage. This rubbing motion causes some frictional resistance to the relative rotation between the inner race and the outer race. Thus, this friction increases the frictional torque, and, in particular in high speed ranges, considerable heat is generated in contact regions, with the result that power is lost, the contact regions are excessively worn out, and temporary destruction of oil film may occur, these leading to various problems such as the loss of fatigue durability of the bearing and so on.